In recent years, various techniques for assisting a backward parking operation of a vehicle based on a captured image have been proposed. One of the techniques uses a bird's eye view based on a camera-captured image of a rear view of a vehicle selectively displayed for an assistance of the backward parking operation as disclosed in Japanese patent document JP-A-2004-254219.
However, the bird's eye processed rear view of the vehicle was not always helpful for the backward parking operation due to its visibility on a display unit. That is, the bird's eye view usually includes various objects other than a parking lot (e.g., a square area marked on a ground), thereby being distracting in terms of guiding driver's attention to the parking lot itself. In other word's, how to appropriately attract the driver's attention to the parking lot itself has been a problem under consideration.